Replies

1. 
   tom77 | Apr 17, 2007 04:55pm | #1

   David,

   I have been following your adventures without comment so far. What an exciting process. Judging from your comments, I think you are right on. Large central facilities look good on paper, but are inflexible and disruptive when they need service. Also, the use of smaller flexible units permits you to easily add small units of additional capacity.

   Clutter is a problem if you are tight with space. Also, the maintenance of many small DC's could be an issue.

   Your comment on separating chips and dust: It seems to me that a cyclone separator on the central system approach would do that.

   Good luck and keep us posted.

   Tom.

1. 
   ring | Apr 17, 2007 07:16pm | #6

   Tom, and All -

   I should clarify a bit the question of chips and dust.  In fact, maybe someone out there can give me a hand with this as well:

   I plan to burn wood chips and cutoffs as a heat source for the drying kiln.  I have lots of info regarding KCal requirements and such and it makes sense, not only using the resource but otherwise we'd have mountains of debris to dispose of.  But I've been told that we cannot use dust (from wide-belt sanders) or even what comes off the tablesaws for this.  Only planer-sized chips and larger.  The "dust" that gets separated in cyclones is only fine, airborne dust.  If I had a central system, then the small particles from saws would certainly get mixed in with the chips.  So the separate collector for each machine allows us to choose what we burn. 

   Am I making an issue out of nothing? Anyone?

    David Ring

   http://www.touchwood.co.il/?id=1&lang=e

1. 
   tom77 | Apr 17, 2007 08:27pm | #7

   David,It would be next to impossible to "tune" the performance of a cyclone to reliably separate the sawdust and fine particles from larger chips. Usually the cyclone collects almost everything (98% + of sawdust and chips) and passes only the really fine stuff on to the filter. (You can cause the cyclone to be less efficient by creating an air leak in the cannister. This will change the cutoff in particle size separation.) If your requirement for fuel is real, then I don't see any economic alternative to your plan. I would want to challenge the requirement a little, just to make sure it is real.Good luck, Tom.

2. 
   AzDiscDog | Apr 17, 2007 10:54pm | #8

   Hi David,Sorry to belabor a point here, but why can't you use the dust in the kiln? Or more precisely, why have you been told you can't?The only thing I can imagine is a flash-fire hazard from the dust. I'm more familiar with pottery / glass / ceramic kilns than wood drying kilns. And the pottery kilns run HOT, certainly enough to start up a flash fire from suspended dust being thrown into the mix. Have you read Bill Pentz's site regarding cyclones? It's worth taking a look into the design of the cyclone to tweak the efficiency. Some of his research comes from agriculture cyclones where the risk of a flash-fire from suspended dust is very, very real. In your case, you'd probably tweak it the *wrong* way to push more dust past the impeller instead of being captured down the funnel.If the fire-hazard is your burning issue (sorry about the pun), then I'm not sure how you're going to get around that. I would think that ANY DC is going to combine some degree of dust with the shavings. Glen
   "trying to put those engineering degrees to work"

2. 
   blewcrowe | Apr 17, 2007 05:25pm | #2

   I think it's a great idea save for one issue, and that is cleaning. To have one master unit and clean/dump it first thing in the morning or last thing at night is one thing. To have to do this with numerous units, well, unless you are an anal drill sargeant about it, it probably aint gonna happen.

1. 
   ring | Apr 17, 2007 06:58pm | #5

   Blewcrowe - I really should have mentioned that the one thing we'll have in abundance is cheap cheap labor.  I can have 2 guys just emptying the DC units all day long, it's of no consequence.

   colebearanimals -   We're making all the parts for wooden houses: posts, rafters, siding, decking, windows, cabinets, etc.  Think modular post and beam, with a touch of African ethnic style. 

     Everything starts in the milling department, which will create huge amounts of debris.  This includes a large gang rip saw, and 2 monster planers - one 2S smooth planer and one 4S molder/planer.  From there the wood goes to various departments: 

      "deck and siding" - shapers and cutoff saws 

      "window and door"  -  shapers, mortisers, drilling stations, wide belt sander

      "cabinets"  -  table saw, edgebander, drilling station, cutoff saws.

      "finishing"  -  various sanding operations

   So the physical division into departments creates a very unequal distribution of chips and dust.

    David Ring

   http://www.touchwood.co.il/?id=1&lang=e

1. 
   colebearanimals | Apr 19, 2007 02:18am | #9

   David,

         Just thought of something. If your budget allowes ( they can be expensive ) how about using a wood chip prossesor that converts wood chips into little pellets? Then you could use everything collected to burn in the drying kiln and/or shop heat etc. Maybe sell any excess.

                    Paul

   ps you're going to need some serious DC

1. 
   ring | Apr 19, 2007 07:49am | #12

   "ps you're going to need some serious DC"Yeah I know, but it goes for everything - serious planing, sawing, shaping, etc. I've run commercial shops all my life, but this is a whole new league for me. I've got 60,000 sq.ft. of factory to equip. Not exactly a basement or garage shop. While I've got professional help on various aspects I still really want the collective thoughts of all you Knotheads. Got to get it right the first time out.thanks,David Ring

   http://www.touchwood.co.il/?id=1&lang=e

1. 
   tinter | Apr 19, 2007 08:57am | #13

   David, if the dust collectors collect chips and dust together, maybe you could have them dumped through a screen to seperate the chips from the dust?  Chris

2. 
   BG | Apr 19, 2007 12:59pm | #14

   Ring,

   I love the thought of smaller DC units to accommodate flexibility in production needs. It just makes sense to modularize operations and flex resources to accommodate design, new technologies and quantity requirements. Also, in an underdeveloped area, buying units where off the shelf replacement parts are available may be very important.

   One business I frequent is Anderson McQuaid in Cambridge/Arlington MA. They process tons of hardwood and make customized moldings. Last year they replaced their DC system...pulled out a monstrous Octopus type system and replaced it with a bigger Octopus type system. My guess is the dust bin gets emptied every 30-40 yards at a time. My point being you may have quantities of chips that go way beyond what your imagining. It might make sense to call a few places like Anderson's or some of the modular home builders in Indiana to get some answers. Good Luck    

3. 
   ring | Apr 19, 2007 04:16pm | #16

   BG,"My point being you may have quantities of chips that go way beyond what your imagining."My imagination is quite vivid on this point. By the end of the first year we need to be able to handle some 40 tons of lumber every month. The chips and cutoffs from that, 12-15 tons worth, should be about enough to power the drying kiln for the same period of time. All this is theoretical for me now, but I have no illusions about what 15 tons of chips looks like. Do you have a personal connection to anyone working in modular home production?David Ring

   http://www.touchwood.co.il/?id=1&lang=e

3. 
   AzDiscDog | Apr 17, 2007 05:55pm | #3

   Hi David,

   I'll qualify myself as not having production experience. So maybe just skip to the next post. :-)

   However, what about noise and dust issues? I realize you have the benefit of not dealing with OSHA or a similar gov't body, but I presume you're still concerned about the health of the workers. I thought one of the primary advantages to central dust collection (for a production shop) was that the cyclone could be placed outside and thereby moving the related noise & dust nuisance outside too.

   I wouldn't underestimate the on-going cost of multiple DCs vs. one central DC. Someone will have to go to each DC and collect the chips, clean the filters, etc... That may push the TCO for multiple DCs higher. Then again, labor may be so cheap for your situation that you don't care.

   Final question / thought -- you state that a central unit wouldn't let you burn the chips? Does that mean you can't use a cyclone for your central unit? I would think a cyclone as the central unit would be perfect -- it would allow you to gather all of the chips in one place.

   Hope that helped and didn't add too much to the noise. :-) And I would jump ship and join you on your project if I weren't married with kids. What you're doing sounds like a lot of fun!

   Glen

4. 
   colebearanimals | Apr 17, 2007 06:20pm | #4

   Hi David,

           Maybe the solution is somewhere in the middle here. I don't know what you'll be manufacturing, but maybe work " cells " might provide you with the flexibility you need. Rather than a separate collector for each machine, one medium size collector ( sized appropriately ) could be connected for each " cell ". For example. If your product requires a shaped, curved part you would have a bandsaw, spindle sander, shaper,etc. in a single " cell " ( CNC not withstanding ).

           Sounds like you have a lot to work out. Hope this stimulates the process.

                           Paul

5. 
   dukeone | Apr 19, 2007 05:07am | #10

   David; A couple of things come to mind: You could have a central system with two motor/blower units. If one failed you would still be up and running maybe just a bit slower. If both motors could handle the load then you would not skip a beat. Have the electrician put in an alternator: that would switch back and forth between units equalizing the wear on each. Another idea is that Felder makes a dust collector with a "bricking" device that compacts dust and chips into briquettes for burning. Probably costs an arm and a leg but might work for your situation.

   http://usa.felder-gruppe.at/?page=maschinen_details&xat_code=eaefb1585bdcce360c6c&parent=37bd7666a4c8f3bb595f

   Good luck, Duke

    

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1. 
   ring | Apr 19, 2007 07:35am | #11

   Duke, I like the idea of 2 motors. If I do go with the central system (as opposed to many individual units) I will try to do it this way.Regarding the pellets - I suspect that it will be too expensive, but I will check the cost.thanks,
   David Ring

   http://www.touchwood.co.il/?id=1&lang=e

1. 
   eddiefromAustralia | Apr 19, 2007 01:07pm | #15

   Ring,You could stick a drop-out chamber in front of the dust collector (also known as a plenum chamber.)The heavy stuff will fall out, the lighter stuff will remain suspended in the airstream and make it's way to the dust collector.This is the cheapest way to separate out the chips from the dust.Now, as to burning the mixture in a boiler, I can't comment. I used to burn the lot in a cement kiln. Dust and heat weren't a problem. Try asking your local boiler engineers or the manufacturers' agents for their comments. I'd imagine it may have something to do with too wide a size distribution in the feed causing a fairly dense packing density that would give you too high a dP across the fuel bed. Just a guess, however, with no idea at all of the type of fuel and boiler design.Trust that this may help.Cheers,eddieEdit: timber chips are renowned for bridging over hoppers - they need specialised extraction systems - don't skip this step as it'll bite you later. I'd get the bin design done by a materials handling expert, especially the fuel bin going to the boiler.

   Edited 4/19/2007 6:10 am by eddiefromAustralia

1. 
   ring | Apr 19, 2007 05:05pm | #17

   Eddie and All,Thanks for your thoughts. I have a meeting coming up with a DC expert, and I'll let you know what we decide. Right now I'm leaning towards a combination - a central system to handle the milling department (large planers and rip saw) which produces most of the chip volume, and separate units for all the rest of the machines. I don't yet understand the real limitations on what we can burn effectively. But the combined approach I'm contemplating would make it simple to control as required.David Ring

   http://www.touchwood.co.il/?id=1&lang=e